The present invention relates generally to metal rolling mills and more particularly to a method and apparatus of correcting camber in a rolled metal workpiece.
Camber, as the term is employed in the present specification, refers to a curvature along the length of a metal workpiece which often becomes more pronounced as the length increases and is usually the result of a greater elongation along one side of the workpiece than along the other side. The workpiece then assumes, when viewed from the top, a generally arcuate configuration.
Camber in a rolled metal workpiece results in waste, in the case of plate products, and stand threading or coil entry problems, in the case of tandem mills. The waste in plate product results from the additional side scrap when shearing rectangular plates from the curved, untrimmed "pattern". This additional scrap must be allowed for in the target dimensions for the rolling operation. Inadequate allowances will increase underwidth rejects. Both the added allowance and the increased rejects reduce process yield making it important to minimize the average rolled camber. In tandem rolling stands, severe camber or curvature may prevent proper threading of subsequent stands or coilers.
It has been past practice to provide camber correction through operator intervention. That is, the mill operator by visual inspection observed the workpiece and, based upon his experience and judgment, adjusted the mill work rolls. This has resulted in production losses either through reduced threading speeds necessary to accommodate the operator's manual corrections, or through direct material loss where these correction were inadequate.